Develop Reference

View not updated from callback method

I am fetching data from database. My views are updating only first time when I open the activity. Then when I again open the activity, my views are not updated.(Activity is starting again, hence onCreate() is called again & all settings are same). If I getText() after setting the text, I am getting proper values in log but nothing is displayed in view.
Here is my code snippet:
//My Call Back method
#Override
public void onRatingDataLoaded(ReviewJsonModel review) {
int ratingCount = 0, ownRating = 0;
String averageRating = "0";
if (review != null) {
ratingCount = review.review_count;
DecimalFormat format = new DecimalFormat("##.00");
averageRating = format.format(review.rating);
if (review.ownreviews != null) {
try {
ownRating = Integer.parseInt(review.ownreviews.rating);
} catch (NumberFormatException e) {
e.printStackTrace();
}
}
} else {
// do something
}
mTotalRatingCount.setText(String.format(getResources().getString(R.string.review_count), ratingCount));
mAverageRating.setText(averageRating);
// Log.v("LoggingReview", mTotalRatingCount.getText().toString().trim);
myRating.setRating(ownRating);
}
//Here I am setting listner as well as loading data.
public void loadReviewData(RatingDataLoadListener listener, int destinationId) {
if (mDataLoadListener == null)
mDataLoadListener = listener;
new getReviews().execute(destinationId);
}
Next is my asyntask
private class getReviews extends AsyncTask<Integer, Void, ReviewJsonModel> {
#Override
protected ReviewJsonModel doInBackground(Integer... integers) {
Cursor appCursor = mRatingApi.getDestinationReview(integers[0]);
ReviewJsonModel mReviewData = new ReviewJsonModel();
if (appCursor != null && appCursor.getCount() > 0) {
appCursor.moveToFirst();
while (!appCursor.isAfterLast()) {
mReviewData = getDocument(appCursor);
appCursor.moveToNext();
}
appCursor.close();
}
return mReviewData;
}
#Override
protected void onPostExecute(ReviewJsonModel result) {
super.onPostExecute(result);
if (mDataLoadListener != null)
mDataLoadListener.onRatingDataLoaded(result);
}
}
Can't find cause of problem. Any help is appreciated.

Looks like there is callback issue, can you please try below
public void loadReviewData(RatingDataLoadListener listener, int destinationId) {
mDataLoadListener = listener;
new getReviews().execute(destinationId);
}

Sync Sqlite Database With Remote Server in Android

I store data with sqlite database from remote server with AsyncTask..
I have used Retrofit to fetch data, and now I want to store that data into sqlite... I already have DatabaseHelper.class , Model Class and NavigationDrawer in that i am performing AsynckTask in MainActivity.
private class getDataToSqlite extends AsyncTask<Post, Void, Void>{
#Override
protected Void doInBackground(Post... params) {
apiInterface.getContacts().enqueue(new Callback<List<Post>>() {
#Override
public void onResponse(Call<List<Post>> call, Response<List<Post>> response) {
if (response.isSuccessful()){
contacts = response.body();
for (int i=0; i < contacts.size(); i++){
Post post = contacts.get(i);
SaveToDatabase task = new SaveToDatabase();
task.execute(post);
adapter.addPost(post);
}
}else {
}
}
#Override
public void onFailure(Call<List<Post>> call, Throwable t) {
Toast.makeText(getApplicationContext(), "Error" + t.toString(), Toast.LENGTH_SHORT).show();
}
});
return null ;
}
}
private class SaveToDatabase extends AsyncTask<Post, Void , Void> {
#Override
protected Void doInBackground(Post... params) {
Post post = params[0];
try {
myDb.addData(post);
} catch (Exception e) {
Log.d(TAG, e.getMessage());
}
return null;
}
}
That class present in MainActivity
and i call the class in onCreate
new getDataToSqlite();
where i doing wrong please tell me

You can do something like this that I have already Done :
public boolean SyncCityMasterToDevice() {
try {
DatabaseHandler db = new DatabaseHandler(mContext);
db.dbDelete(TableCityMaster.TABLE);
List<CityMaster> cityMasterList = ServerRepo.getCities();
db.dbAddCity(cityMasterList);
Log.d(TAG, "SyncCityMasterToDevice: ");
return true;
} catch (IOException e) {
e.printStackTrace();
return false;
}
}
ServerRepo.getCities(); is a Retrofit Call.
I have called SyncCityMasterToDevice() method in an Async task
`DatabaseHandler` is the Database Helper Class.

How to manually call observer.onNext in rxJava

I am relatively new to RxJava/RxAndroid. I have been using AsyncTask to do my long running tasks before now.
I have converted most of my AsyncTask to RxJava but this one.
The particular problem I am having is calling something like AsyncTask's publishProgress(params); in
the background thread. I need to do this to update the progress of a ProgressBar.
First this is the code in AsyncTask
private static class AddBooksToDatabase extends AsyncTask<String, String, String> {
//dependencies removed
AddBooksToDatabase(AddBooksDbParams params) {
//Removed assignment codes
}
#Override
protected String doInBackground(String... strings) {
//Initializing custom SQLiteOpenHelper and SQLite database
File mFile = new File(mFolderPath);
int booksSize = getFilesInFolder(mFile).size();
String[] sizeList = {String.valueOf(booksSize)};
//The first publishProgress is used to set the max of the progressbar
publishProgress(sizeList);
for (int i = 0; i < booksSize; i++) {
//publishProgress with current item, current file
publishProgress(String.valueOf(i), getFilesInFolder(mFile).get(i).getName());
//Inserting current items in database. Code removed
}
return null;
}
#Override
protected void onPreExecute() {
//Show ProgressBar
}
#Override
protected void onPostExecute(String s) {
//Hide ProgressBar
}
#Override
protected void onProgressUpdate(String... values) {
super.onProgressUpdate(values);
if (values.length == 1) {
//The first call to publishProgress
mProgressBar.setMax(Integer.parseInt(values[0]));
} else {
//Subsequent calls to publish progress
Log.i(TAG, "Current item is " + values[0] + " and current file is " + values[1]);
infoText.setText(values[1]);
mProgressBar.setProgress(Integer.parseInt(values[0]), true);
}
}
#Override
protected void onCancelled() {
cancel(true);
}
}
Code Using RxJava
final Observable<String[]> addBooksObserver = Observable.create(new Observable.OnSubscribe<String[]>() {
#Override
public void call(Subscriber<? super String[]> subscriber) {
subscriber.onNext(setAddSubscription());
subscriber.onCompleted();
}
})
.subscribeOn(Schedulers.io())
.observeOn(AndroidSchedulers.mainThread());
private String[] setAddSubscription() {
S//Initializing custom SQLiteOpenHelper and SQLite database
File mFile = new File(mFolderPath);
int booksSize = getFilesInFolder(mFile).size();
String[] sizeList = {String.valueOf(booksSize)};
//The first publishProgress is used to set the max of the progressbar
addBooksObserver.doOnNext(addReturnParams(String.valueOf(sizeList.length), null, null));
for (int i = 0; i < booksSize; i++) {
EpubReader reader = new EpubReader();
//publishProgress with current item, current file*
addBooksObserver.doOnNext(addReturnParams(String.valueOf(sizeList.length),
String.valueOf(i), getFilesInFolder(mFile).get(i).getName()));
//Inserting current item in database. Code removed
}
return null;
}
private String[] addReturnParams(String totalItems, String currentItem, String currentFile) {
return new String[]{totalItems, currentItem, currentFile};
}
The problem is that lines addBooksObserver.doOnNext(addReturnParams( are displaying this error
doOnNext (rx.functions.Action1) cannot be applied to (java.lang.String[])
I don't know have any idea how to fix this because I thought that since setAddSubscription() and addReturnParams(String totalItems, String currentItem, String currentFile) are returning String array then this shouldn't be a problem. Please can you help me out?

you just have to pass the values to the onNext method of your subscriber, not the doOnNext method of your observable!
you also have to subscribe to the service. try something like this for your obserable:
Observable.create(new Observable.OnSubscribe<String[]>() {
#Override
public void call(Subscriber<? super String[]> subscriber) {
setAddSubscription(subscriber);
subscriber.onCompleted();
}
})
.subscribeOn(Schedulers.io())
.observeOn(AndroidSchedulers.mainThread())
.subscribe(new Subscriber<String[]>() {
#Override
public void onCompleted() {
// handle 'oparation is done'
}
#Override
public void onError(Throwable e) {
}
#Override
public void onNext(String[] values) {
if (values.length == 1) {
//The first call to publishProgress
mProgressBar.setMax(Integer.parseInt(values[0]));
} else {
//Subsequent calls to publish progress
Log.i(TAG, "Current item is " + values[0] + " and current file is " + values[1]);
infoText.setText(values[1]);
mProgressBar.setProgress(Integer.parseInt(values[0]), true);
}
}
});
you also need to modify your private methods a little bit:
private void setAddSubscription(Subscriber<? super String[]> subscriber) {
//Initializing custom SQLiteOpenHelper and SQLite database
File mFile = new File(mFolderPath);
int booksSize = getFilesInFolder(mFile).size();
String[] sizeList = {String.valueOf(booksSize)};
//The first publishProgress is used to set the max of the progressbar
subscriber.onNext(addReturnParams(String.valueOf(sizeList.length), null, null));
for (int i = 0; i < booksSize; i++) {
EpubReader reader = new EpubReader();
//publishProgress with current item, current file*
subscriber.onNext(addReturnParams(String.valueOf(sizeList.length),
String.valueOf(i), getFilesInFolder(mFile).get(i).getName()));
//Inserting current item in database. Code removed
}
}
private String[] addReturnParams(String totalItems, String currentItem, String currentFile) {
return new String[]{totalItems, currentItem, currentFile};
}

You can use Subject to call onNext() manually like this:
Subject<Event> event = Subject.create();
Now call the onNext() for sending event like:
event.onNext("event");
Finally you can return Observable by using this code:
event.toFlowable(BackpressureStrategy.LATEST)
.toObservable();

Your Observer should be like Observable.create(new Observable.OnSubscribe<String>() & in your call method you should loop through the StringArray & pass it to onNext for example:
#Override
public void call(Subscriber<? super String> subscriber) {
for(String val : setAddSubscription()) {
subscriber.onNext(val);
}
subscriber.onCompleted();
}
now onNext shall return you individual items & onCompleted will be called upon the loop is finished.
Edit
myObserver.subscribe(new Subscriber<String>() {
#Override
public void onCompleted() {
// handle completion.
}
#Override
public void onError(Throwable e) {
}
#Override
public void onNext(String value) {
// do whatever with each value passed to onNext
}
});

Observable.create(emitter -> {
for (int i = 0; i < 10; i++) {
int[] ii = {i, i * 2};
emitter.onNext(ii);
}
emitter.onComplete();
}).observeOn(AndroidSchedulers.mainThread()).subscribeOn(Schedulers.io()).subscribe(o -> {
// update progress
int[] i = (int[]) o;
Toast.makeText(SearchActivity.this, "oftad " + i[0] + " - " + i[1], Toast.LENGTH_SHORT).show();
}, t -> {
// on error
Toast.makeText(SearchActivity.this, t.getMessage(), Toast.LENGTH_SHORT).show();
}, () -> {
// progress tamom shod
Toast.makeText(SearchActivity.this, "completed", Toast.LENGTH_SHORT).show();
});

How can i print arraylist from class AsyncTask?

I want to print an ArrayList. I have receive value arraylist from class AsyncTask, in MainActivity, I have value ArrayList, but when I print ArrayList, my app is not working. Please help me!
MainActivity
{
executeLoadProduct();
arraylistgroup = new ArrayList<String>();
arraylistgroup=TaskLoadProductGroup.getvaluearraylist();
String[] mStringArray = new String[arraylistgroup.size()];
mStringArray = arraylistgroup.toArray(mStringArray);
for (int i = 0; i < mStringArray.length; i++) {
System.out.println("string is2" + (String) mStringArray[i]);
}
executeLoadProduct
private void executeLoadProduct() {
// execute task load product
loadProductGroup = new TaskLoadProductGroup(MainActivity.this);
loadProductGroup.execute();
}
AsyncTask
public class TaskLoadProductGroup extends AsyncTask<String, Void, ArrayList<String>> {
private ActionBarActivity actionBarActivity;
private Context context;
private static ArrayList<String> arrayListgroup;
public TaskLoadProductGroup(ActionBarActivity actionBarActivity) {
this.actionBarActivity = actionBarActivity;
this.context = actionBarActivity.getApplicationContext();
}
#Override
protected void onPreExecute() {
///show progress loading
super.onPreExecute();
}
#Override
protected ArrayList<String> doInBackground(String... url) {
ArrayList<String> listProductgroup = null;
try {
Server server = new Server();
ResListProduct resListProduct = server.getListProducts(context);
//init list item for listview home product
listProductgroup = initItemProduct(resListProduct);
} catch (Exception e) {
}
return listProductgroup;
}
public static ArrayList<String> initItemProduct(ResListProduct rsProduct) {
List<GroupProduct> groups = rsProduct.getGroups();
arrayListgroup = new ArrayList<String>();
for (GroupProduct group : groups) {
// add header group
String s = group.getName();
arrayListgroup.add(s);
}
getvaluearraylist();
// getVarialty();
return arrayListgroup;
}
public static ArrayList<String> getvaluearraylist()
{
return arrayListgroup;
}
#Override
protected void onPostExecute(ArrayList<String> listProductgroup) {
super.onPostExecute(listProductgroup);
}
}

I couldn't identify why are you doing so complex code to print the ArrayList. You can just print that inside onPostExecute method like this,
#Override
protected void onPostExecute(ArrayList<String> listProductgroup) {
super.onPostExecute(listProductgroup);
for (String value : listProductgroup){
Log.d("myTag", value);
}
}
OR
Use loadProductGroup.execute().get() method, but remember this will freeze your UI.

Reusable AsyncTask by any activity

My goal is to have an AsyncTask that
can execute multiple times (one task at a time of course)
its current task can be cancelled
can be used by any activity
can execute many different tasks
does not have any problem with screen rotation (or phonecalls etc)
To achieve that i have created the classes shown below. But my experience with (and understanding of) threads is very limited. And since i don't know of any way to debug multiple threads, there is no way (for me) of knowing if this is going to work or not. So what i'm really asking is: Is this code ok?
And since there is no code that it is currently using this, here's an example use for it:
Data2Get d2g = new Data2Get(this, Data2Get.OpCountNumbers);
d2g.setParam("up2Num", String.valueOf(800));
LongOpsRunner.getLongOpsRunner().runOp(d2g);
So, here we go. This is the interface that every activity that wants to execute a long task (operation - op) should implement:
public interface LongOpsActivity {
public void onTaskCompleted(OpResult result);
}
This is a class to enclose any result of any task:
public class OpResult {
public LongOpsActivity forActivity;
public int opType;
public Object result;
public OpResult(LongOpsActivity forActivity, int opType, Object result){
this.forActivity = forActivity;
this.opType = opType;
this.result = result;
}
}
And finally the big part, the singleton async task class:
import java.util.HashMap;
import java.util.Map.Entry;
import java.util.concurrent.locks.Condition;
import java.util.concurrent.locks.ReentrantLock;
import android.os.AsyncTask;
public class LongOpsRunner extends AsyncTask<Void, OpResult, Void> {
public class Data2Get implements Cloneable {
// one id for each operation
public static final int OpCountNumbers = 1;
public static final int OpCountLetters = 2;
public LongOpsActivity forActivity;
public int opType;
private HashMap<String, String> params = new HashMap<String, String>();
public Data2Get(LongOpsActivity forActivity, int opType) {
this.forActivity = forActivity;
this.opType = opType;
}
public void setParam(String key, String value) {
params.put(key, value);
}
public String getParam(String key) {
return params.get(key);
}
public void clearParams() {
params.clear();
}
#Override
protected Object clone() throws CloneNotSupportedException {
// deep clone
Data2Get myClone = (Data2Get) super.clone();
myClone.clearParams();
for (Entry<String, String> entry : params.entrySet()) {
myClone.setParam(new String(entry.getKey()), new String(entry.getValue()));
}
return myClone;
}
}
private class IntermediateResult extends OpResult {
public IntermediateResult(LongOpsActivity forActivity, int opType, Object result) {
super(forActivity, opType, result);
}
}
// not really needed
private class FinalResult extends OpResult {
public FinalResult(LongOpsActivity forActivity, int opType, Object result) {
super(forActivity, opType, result);
}
}
private final ReentrantLock lock = new ReentrantLock();
private final Condition executeOp = lock.newCondition();
private volatile boolean finished = false;
private volatile boolean waiting = true;
private volatile boolean shouldCancel = false;
private volatile boolean activityHasBeenNotified = true;
private Data2Get startingOpParams = null;
private Data2Get currentOpParams = null;
private FinalResult currentOpResult;
protected Void doInBackground(Void... nothing) {
try {
lock.lockInterruptibly();
do {
waiting = true;
while (waiting) {
executeOp.await();
}
shouldCancel = false;
activityHasBeenNotified = false;
boolean opCancelled = false;
try {
currentOpParams = (Data2Get) startingOpParams.clone();
} catch (CloneNotSupportedException cns) {
// do nothing
}
switch (currentOpParams.opType) {
case Data2Get.OpCountNumbers:
int numberCounter = 0;
int numLoopCount = 0;
while ((!opCancelled) & (numLoopCount <= 5000000)) {
if (!shouldCancel) {
numberCounter = (numberCounter + 1)
% Integer.parseInt(currentOpParams.getParam("up2Num"));
if (numberCounter == 0) {
numLoopCount++;
publishProgress(new IntermediateResult(
currentOpParams.forActivity,
currentOpParams.opType,
"Numbers loop count:" + numLoopCount));
}
} else {
opCancelled = true;
activityHasBeenNotified = true;
}
if (!opCancelled) {
currentOpResult = new FinalResult(
currentOpParams.forActivity,
currentOpParams.opType,
"Numbers loop completed.");
publishProgress(currentOpResult);
}
}
break;
case Data2Get.OpCountLetters:
int letterLoopCount = 0;
char ch = 'a';
while (!opCancelled & (letterLoopCount <= 5000000)) {
if (!shouldCancel) {
ch++;
if (Character.toString(ch).equals(currentOpParams.getParam("up2Letter"))) {
ch = 'a';
letterLoopCount++;
publishProgress(new IntermediateResult(
currentOpParams.forActivity,
currentOpParams.opType,
"Letters loop count:" + letterLoopCount));
}
} else {
opCancelled = true;
activityHasBeenNotified = true;
}
if (!opCancelled) {
currentOpResult = new FinalResult(
currentOpParams.forActivity,
currentOpParams.opType,
"Letters loop completed.");
publishProgress(currentOpResult);
}
}
break;
default:
}
} while (!finished);
lock.unlock();
} catch (InterruptedException e) {
// do nothing
}
return null;
}
public void cancelCurrentOp() {
shouldCancel = true;
}
#Override
protected void onProgressUpdate(OpResult... res) {
OpResult result = res[0];
if (result instanceof IntermediateResult) {
// normal progress update
// use result.forActivity to show something in the activity
} else {
notifyActivityOpCompleted(result);
}
}
public boolean currentOpIsFinished() {
return waiting;
}
public void runOp(Data2Get d2g) {
// Call this to run an operation
// Should check first currentOpIsFinished() most of the times
startingOpParams = d2g;
waiting = false;
executeOp.signal();
}
public void terminateAsyncTask() {
// The task will only finish when we call this method
finished = true;
lock.unlock(); // won't this throw an exception?
}
protected void onCancelled() {
// Make sure we clean up if the task is killed
terminateAsyncTask();
}
// if phone is rotated, use setActivity(null) inside
// onRetainNonConfigurationInstance()
// and setActivity(this) inside the constructor
// and all that only if there is an operation still running
public void setActivity(LongOpsActivity activity) {
currentOpParams.forActivity = activity;
if (currentOpIsFinished() & (!activityHasBeenNotified)) {
notifyActivityOpCompleted(currentOpResult);
}
}
private void notifyActivityOpCompleted(OpResult result) {
if (currentOpParams.forActivity != null) {
currentOpParams.forActivity.onTaskCompleted(result);
activityHasBeenNotified = true;
}
}
private static LongOpsRunner ref;
private LongOpsRunner() {
this.execute();
}
public static synchronized LongOpsRunner getLongOpsRunner() {
if (ref == null)
ref = new LongOpsRunner();
return ref;
}
public Object clone() throws CloneNotSupportedException {
throw new CloneNotSupportedException();
}
}
I hope someone helps with making this work, as it would be very useful not only for me, but many other people out there. Thank you.

Try Loaders. I switched from simple AsyncTasks to AsyncTaskLoaders and they solve lots of problems. If you implement a Loader as a standalone class, it would meet all of your requirements, especially when it comes to rotation which is the biggest issue with old AsyncTask.